XYY syndrome

He would spend long stretches of time alone in his crib, seemingly content to just sit there staring into nothing with this blank, vacant expression on his face.

Now, Art was born with a chromosomal condition known as Jacobs syndrome or XYY syndrome, meaning he had an extra Y chromosome.

People with XYY syndrome have, or can have, an increased likelihood of learning difficulties, delayed speech and language development, and certain behavioral, social, and emotional challenges.

For a time, researchers also believed that an extra Y chromosome might predispose men to aggression or violent behavior, an idea that earned the XYY, uh, chromosome or condition the nickname supermale syndrome.

So for, like, a hot minute, science briefly discovered the alpha male before podcasts did, which I think is something.

The, quote-unquote, supermale syndrome theory has since fallen apart.

Having XYY syndrome does not mean that someone is biologically destined to become a violent maniac.

But one detail from Art's infancy does become interesting in hindsight.

Worth naming plainly here too, since it often surprises people who assume biology itself draws a simple clean line, it doesn't.

Documented natural chromosome variations include XXY, known as Klinefelter syndrome, typically presenting as male, XYY, sometimes called Jacob syndrome, also typically male, XXX, sometimes called the triple X syndrome, typically female, and XO, a single X chromosome with no second sex chromosome at all, known as Turner syndrome, also typically female.

Some people carry even rarer combinations.

And beyond chromosome count itself, there are cases where the SRY gene, the specific gene on the Y chromosome that actually triggers male development, get damaged, producing someone with XY chromosomes who develops as female, or copied over onto an X chromosome instead, producing someone with XX chromosomes who develops as male.